The Earth's atmosphere has several ionization layers known as the D layer, E layer and F1 and F2 layers created by the sun and solar radiation producing ions and electrons that recombine slowly due to the low air density in the upper region of the Earth's atmosphere (The ARRL Antenna Book, Radio Wave Propagation, The American Radio Relay League (1991) 23-1). The F2 layer that is around 100 km to 500 km from the surface of the Earth depending on the season of the year, the latitude, the time of day and the sun's brightness, is permanently stable, i.e., it is present throughout the entire 24 hour day. The D layer and E layer tend only to be present during solar radiation of the Earth's atmosphere, i.e., not at night.
For almost a century, the electromagnetic waves existing on the surface of Earth's ionization layers have been measured and recorded at a single point, i.e., zero-dimensionally, from the Earth's surface producing ionosonde data (https://en.m.wikipedia.org/wiki/Ionosonde).
The detected surface waves on the ionization layer are created by atmospheric disturbances due to solar, geomagnetic and meteorological events such as the sun spot activities having ˜11 year cycle, yearly rotation of the Earth around the sun, seasonal changes of the Earth and shorter frequency, large atmosphere disturbing events such as typhoons, volcanoes, earthquakes, etc. Most of the waves on the surface of the ionization layer are believed to be due to meteorological events (FIG. 2, H. Rishbeth, “F-region links with the lower atmosphere?” J. Atmosphere and Solar-Terrestrial Physics, Vol. 68, Issue 3-5 (2006) 469-478.). The surface waves appear to have many sources, to be moving and to have a wide range of frequencies and amplitudes.
The use of beams of radiation to obtain information about an object by detecting the amplitude or phase of the beam is well known for scientific purposes. The beam of radiation, sometimes known as a carrier wave, can carry the information of the object. For example, the phase information of a beam that passes through or reflects from an object can provide information on the object's temperature, pressure, composition, magnetic fields or electric fields, whereas amplitude measurements can provide information on the opaqueness or density of the object. The beams are comprised of waves of radiation, where a wave, Φ, can be described as having both an amplitude, A, and phase, θ, described mathematically as,Φ=A exp(θ)  1)
The information obtained from the method depends on whether it is detecting the amplitude or both the amplitude and phase of a beam's wave. If the method measures only a beam's amplitude only density differences in the object are reported. This is a limitation of the technology as it does not provide information such as an object's temperature, pressure, composition, magnetic fields or electric fields. If the method measures the beam's phase, object information such as electromagnetic waves that exist on an object's surface can be revealed. If the method uses a detector comprising of a two-dimensional array of radio wave receivers or antennae, a two-dimensional phase image of the waves existing on the object's surface, i.e., the ionization layer's surface, can be revealed. From the phase shifts produced within the phase image, a measurement of the amplitudes, frequencies and directions (the so-called wave vectors) of the waves existing on the surface of the ionization layer is made possible.
Radio waves, typically from about 3 Mega Hertz (MHz) to about 7 MHz and as high as 10 MHz, when emitted from the surface of the Earth, referred to as sky waves, can reflect off the Earth's ionization layers and return back to Earth. The reflection of radio waves off the ionization layer is commonly used to extend the reach of radio waves for transmission and communication purposes (The ARRL Antenna Book, Radio Wave Propagation, The American Radio Relay League (1991) 23-1). Sky waves are also being used to produce ionosondes using one antenna. This method cannot be used to obtain phase information.
What is needed is a system that can accurately image waves on the lower surface of one or more layers the ionosphere in order to track atmospheric disturbances and conditions, including those caused by changes to the climate, fires, volcanoes, and the like. It would be advantageous if the location of the atmospheric condition or disturbance could be identified. It would be of further advantage if there was a method of obtaining accurate data about the surface waves of the ionosphere.